Читать книгу Bovine Reproduction - Группа авторов - Страница 301

Hemi‐ or unilateral castration should be considered in bulls with unilateral testicular disease. When one testicle is inflamed, the heat thus generated affects the contralateral testicle and the reversibility of degenerative change depends on the severity and duration of the insult [12]. Valuable animals with unilateral hematoceles, hyrdrocleles, orchitis, periorchitis, or testicular rupture may be able to resume breeding soundness with unilateral castration.

Although unilateral castration is not an emergency procedure, the prognosis for return to fertility improves if surgery is performed early in the disease process. Early intervention can reduce further insult to the contralateral testicle generated by inflammation, with less likelihood that the testicle will undergo irreversible degeneration. Most bulls will return to fertility following surgery if the remaining testicle is not severely compromised [10, 21, 22]. Compensatory hypertrophy in the normal testis should allow the bull to subsequently produce up to 75% of normal sperm capacity. Therefore, advise owners that restrictions may be necessary following surgery. Additionally, although a bull may be productive in a herd situation, a unilaterally castrated bull will not pass a standardized breeding soundness evaluation and is therefore ineligible for certain shows or sales [10].

In preparation for surgery the bull should be withheld from feed for 48 hours and water for 12 hours. Surgery is performed with the bull restrained in lateral recumbency under general anesthesia or heavy sedation and regional or local anesthesia. Regional anesthesia can be accomplished with the use of a pudendal nerve block, or local anesthetic can be injected into the neck of the scrotum and the spermatic cord. Antibiotics are administered prior to surgery and continued for at least five days post‐surgery. Non‐steroidal anti‐inflammatories should also be administered immediately prior to surgery. The scrotum is clipped and prepped for aseptic surgery [10, 23]. On the lateral aspect of the scrotum an elliptical skin incision is made approximately the length of the testicle, preserving the parietal vaginal tunic (Figure 18.9). The affected testicle within the parietal vaginal tunic is bluntly dissected away from the surrounding scrotal fascia (Figure 18.10). If the condition is chronic, variable amounts of fibrous tissue and adhesions of the parietal and visceral vaginal tunics may be encountered. At this point the decision is made whether an open or closed castration should be pursued. An open castration allows for more careful ligation of the vasculature but does expose the surgery site to potential contamination from the contents of the parietal tunic. A closed castration is typically performed by the author to limit contamination of the surgical site. Both techniques are described below.

Figure 18.9 Elliptical skin incision on lateral aspect of scrotum.

Source: Image courtesy of Richard Hopper and Heath King.

Figure 18.10 Testicle within parietal vaginal tunic bluntly dissected from scrotal fascia.

Source: Image courtesy of Richard Hopper and Heath King.

To perform an open castration, a vertical incision is made through the parietal tunic sufficiently long to remove the testis and exteriorize the testicle and spermatic cord (Figures 18.11). The spermatic artery, vein, and ductus deferens are isolated and double ligated with #0 chromic gut 8 cm proximal to the pampiniform plexus and transected between the two ligatures (Figure 18.12). The vaginal tunic is then transected and the external cremaster muscle is ligated and transected distal to the stump of the spermatic cord (Figure 18.13). The vaginal tunic is closed with an inverting pattern such as a Connell or Parker–Kerr using #0 chromic gut (Figure 18.14). To perform the closed castration, the spermatic cord is ligated proximal to the pampiniform plexus with a combination of one transfixing ligature and two circumferential Miller's knot ligatures using #4 polyglactin suture (Figure 18.15). The spermatic cord is then transected distal to the ligatures with emasculators. For either technique, the scrotal fascia and tunica dartos are closed with #0 or larger chromic gut in a simple continuous pattern being careful to eliminate dead space. The skin is then closed with non‐absorbable suture in a continuous pattern of the surgeon's choice (Figure 18.16).

Figure 18.11 Parietal vaginal tunic incised and testicle exposed.

Source: Image courtesy Darcie Sidelinger & Heath King.

Figure 18.12 Schematic of double ligation and transection of spermatic cord and vessels.

Figure 18.13 Transected stump of vaginal tunic following inverting suture closure.

Source: Image courtesy Darcie Sidelinger & Heath King.

Figure 18.14 Schematic of inverting closure of vaginal tunic.

Figure 18.15 Ligation of spermatic cord for a closed castration.

Source: Image courtesy of Richard Hopper and Heath King.

Figure 18.16 Scrotal skin incision closed with continuous interlocking pattern.

Source: Image courtesy of Richard Hopper and Heath King.

Postoperative swelling can be reduced by wrapping the scrotum in 4 inches of elastic adhesive tape (Figure 18.17). The bandage should be removed in 24–48 hours. Skin sutures are removed in 10–14 days and the bull can return to service when the spermiogram returns to normal. Normal bulls undergoing unilateral orchiectomy had normal spermiograms by 14 days after surgery [16]. Bulls with unilateral scrotal pathology and transient testicular degeneration of the remaining testicle should be expected to return to normal sperm production approximately 60 days after removal of the diseased or injured testicle [17]. However, if the surgery is performed during the warmer months of the year, normal testicular function may not resume until ambient temperatures moderate.

Figure 18.17 Postoperative bandaging of scrotum to minimize swelling.

Source: Image courtesy of Richard Hopper.